<?php

class StreamReader {

    function read($bytes) {
        return false;
    }

    // should return new position
    function seekto($position) {
        return false;
    }

    // returns current position
    function currentpos() {
        return false;
    }

    // returns length of entire stream (limit for seekto()s)
    function length() {
        return false;
    }
}
;

class StringReader {

    var $_pos;

    var $_str;

    function StringReader($str = '') {
        $this->_str = $str;
        $this->_pos = 0;
    }

    function read($bytes) {
        $data = substr($this->_str, $this->_pos, $bytes);
        $this->_pos += $bytes;
        if (strlen($this->_str) < $this->_pos)
            $this->_pos = strlen($this->_str);
        
        return $data;
    }

    function seekto($pos) {
        $this->_pos = $pos;
        if (strlen($this->_str) < $this->_pos)
            $this->_pos = strlen($this->_str);
        return $this->_pos;
    }

    function currentpos() {
        return $this->_pos;
    }

    function length() {
        return strlen($this->_str);
    }
}
;

class FileReader {

    var $_pos;

    var $_fd;

    var $_length;

    function FileReader($filename) {
        if (file_exists($filename)) {
            
            $this->_length = filesize($filename);
            $this->_pos = 0;
            $this->_fd = fopen($filename, 'rb');
            if (! $this->_fd) {
                $this->error = 3; // Cannot read file, probably permissions
                return false;
            }
        } else {
            $this->error = 2; // File doesn't exist
            return false;
        }
    }

    function read($bytes) {
        if ($bytes) {
            fseek($this->_fd, $this->_pos);
            
            // PHP 5.1.1 does not read more than 8192 bytes in one fread()
            // the discussions at PHP Bugs suggest it's the intended behaviour
            $data = '';
            while ($bytes > 0) {
                $chunk = fread($this->_fd, $bytes);
                $data .= $chunk;
                $bytes -= strlen($chunk);
            }
            $this->_pos = ftell($this->_fd);
            
            return $data;
        } else
            return '';
    }

    function seekto($pos) {
        fseek($this->_fd, $pos);
        $this->_pos = ftell($this->_fd);
        return $this->_pos;
    }

    function currentpos() {
        return $this->_pos;
    }

    function length() {
        return $this->_length;
    }

    function close() {
        fclose($this->_fd);
    }
}
;

// Preloads entire file in memory first, then creates a StringReader
// over it (it assumes knowledge of StringReader internals)
class CachedFileReader extends StringReader {

    function CachedFileReader($filename) {
        if (file_exists($filename)) {
            
            $length = filesize($filename);
            $fd = fopen($filename, 'rb');
            
            if (! $fd) {
                $this->error = 3; // Cannot read file, probably permissions
                return false;
            }
            $this->_str = fread($fd, $length);
            fclose($fd);
        } else {
            $this->error = 2; // File doesn't exist
            return false;
        }
    }
}
;

?>
